My personal favourite is Lady Grey which basically tastes like Earl Grey, also very enjoyable, with a hint of citrus - lemons and oranges - it's really a bit of a fruit tea/real tea hybrid though, so it may not be your sort of thing. It's also not especially refreshing, so it's not a very good substitute for water.
English Breakfast tea is also a nice tea, and, as you would expect, is refreshing and awakening for mornings, it's also good for anytime of the day, yet I do prefer to keep it to mornings.
Bookmarks